• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.258-265
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• 1998

Seismic isolation has developed to the point where it may be considered as a viable design alternate for a wide range of building structures. However, it needs to consider various aspects to adopt a suitable isolation system for buildings practically. This report presents the basis for the preliminary design procedure which has been developed for the seismic isolation system using the lead rubber bearings. The design procedures have been developed to ensure that the bearings will safely support the maximum gravity load throughout the life of the structure while they provide a period shift and hysteretic damping during the design earthquake.

• Steel and Composite Structures
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• v.50 no.6
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• pp.643-658
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• 2024

The main aim of this study is to quantify the code seismic design coefficients of the RCS system, which consisted of reinforced concrete columns and steel beams, based on the FEMA P-695 methodology. The underlying intention is to evaluate the seismic performance of the RCS system at the system level rather than the connection level. A set of 24 archetype buildings with a various number of stories, beam span lengths, gravity load levels, and seismic load levels are selected and designed based on the prevailing code requirements. Nonlinear analytical models are developed and validated by experimental tests. The pushover and response history dynamic analyses are conducted to evaluate the required data in the performance quantification process. The results show that the design coefficients suggested by the code are acceptable. However, the level of conservatism is very high. Thus, it is possible to use a larger R-factor in the design process or make some relaxations in the design requirements related to this structural system.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.53-56
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• 2004

Recently, post tension flat plate slab system is widely used for a new slab structural system. Slab-column connections may fail in brittle manner by punching shear. Flat plate slabs have been widely used for gravity load resisting system in buildings. Lateral resistance usually provided by shear walls or moment resisting frames. Since plat plates move together with lateral loading system during earthquake or wind, it is important to evaluate the gravity resistance under a drift experienced by lateral force resisting system during either design earthquake or wind. Thus, this study investigated post tension flat plate slab systems whether they have sufficient strength and deformability to resist gravity loads during specified drift levels. Experimental research was carried out.

• Earthquakes and Structures
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• v.17 no.6
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• pp.623-633
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• 2019

A large number of available concrete buildings designed only considering gravity load that require seismic rehabilitation because of failure to meet plasticity criteria. Using steel bracings are a common type of seismic rehabilitation. The eccentric bracings with vertical link reduce non-elastic deformation imposed on concrete members as well as elimination of probable buckling problems of bracings. In this study, three concrete frames of 10, 15, and 20 stories designed only for gravity load have been considered for seismic improvement using performance-based plastic design. Afterwards, nonlinear time series analysis was employed to evaluate seismic behavior of the models in two modes including before and after rehabilitation. The results revealed that shear link can yield desirable performance with the least time, cost and number of bracings of concrete frames. Also, it was found that the seismic rehabilitation can reduce maximum relative displacement in the middle stories about 40 to 80 percent. Generally, findings of this study demonstrated that the eccentric bracing with vertical link can be employed as a suitable proxy to achieve better seismic performance for existing high rise concrete frames.

• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.405-414
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• 2006

In the present study, a numerical analysis was performed for interior connections of continuous flat plate to analyze the effect of design parameters such as column section shape, gravity load and slab span on the behavioral characteristics of the connections. For the purpose, a computer program for nonlinear FE analysis was developed, and the validity was verified. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, as the length of the cross section of column in the direction of lateral load increases and gravity load increases, the effective area and the maximum shear strength providing the torsional resistance decrease considerably. And as the slab span loaded with relatively large gravity load increases, the negative moment around the connection increases and therefore the strength of connection against unbalanced moment decreases. By considering the effect of design parameters on the strength of the connections, the effective shear strength to calculate the torsional moment capacity of connection was proposed and the effectiveness of the proposed shear strength was verified.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.69-83
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• 2005

In many cases, underground structures are built using conventional above-grade structural systems to carry gravity load. This paper proposes the use of underground arches, termed "buried arches", to support gravity loads, wherein the horizontal thrust of the arch is equilibrated by soil pressure. Because the horizontal soil pressure increases with depth, the depth of the arch may be reduced as the depth below grade increases. Critical to the success of such an approach is a proper accounting of creep and shrinkage for arches made of reinforced concrete. This paper addresses the influence of equilibrium, creep, and shrinkage as they affect the design of the arch from a theoretical perspective. Several examples illustrate the use of buried arches for the design of underground parking structures.

• Steel and Composite Structures
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• v.8 no.1
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• pp.85-98
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• 2008

In this study the progressive collapse potential of three- and nine-story special steel moment frames designed in accordance with current design code was evaluated by nonlinear static and dynamic analyses. It was observed that the model structures had high potential for progressive collapse when a first story column was suddenly removed. Then the size of beams required to satisfy the failure criteria for progressive collapse was obtained by the virtual work method; i.e., using the equilibrium of the external work done by gravity load due to loss of a column and the internal work done by plastic rotation of beams. According to the nonlinear dynamic analysis results, the model structures designed only for normal load turned out to have strong potential for progressive collapse whereas the structures designed by plastic design concept for progressive collapse satisfied the failure criterion recommended by the GSA guideline.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1-4
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• 2008

Flat plate slab has been widely used in high rise building for its remarkable advantages. However, Flat plate structures under lateral load are susceptible to punching shear of the slab-column connection. Exterior slab-column connections has an unsymmetrical critical section for eccentric shear of which perimeter is less than that of interior connection, and hence, around the connection, unbalanced moment and eccentric shear are developed by both gravity load and lateral loads. Therefore, exterior connections is susceptible to punching shear failure. For that reason, this study compare ACI 318-05 to CEB-FIP MC 90 that is based on experiment results and existing data of flat plate exterior connections. This study shows that compared to CEB-FIP MC 90 is more exact about eccentric shear stress, unbalanced moment and Both of all are not suitable in large column aspect ratio. Considering gravity shear ratio, These are suitable but design condition only consider gravity shear ratio. So these should be considered differences from change of design condition

• Advances in concrete construction
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• v.9 no.5
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• pp.503-510
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• 2020

Concrete dams are important structures due to retaining amount of water on their reservoir. So such kind of structures have to be designed against static and dynamic loads. Especially considering on critical importance against blasting threats and environmental safety, dams have to be examined according to the blast loads. This paper aims to investigate structural response of concrete gravity dams under blast loads. For the purpose Sarıyar Concrete Gravity Dam in Turkey is selected for numerical application with its 85 m of reservoir height (H), 255 m of reservoir length (3H), 72 m of bottom and 7 m of top widths. In the study, firstly 3D finite element model of the dam is constituted using ANSYS Workbench software considering dam-reservoir-foundation interaction and a hydrostatic analysis is performed without blast loads. Then, nearly 13 tons TNT explosive are considered 20 m away from downstream of the dam and this is modeled using ANSYS AUTODYN software. After that explicit analyses are performed through 40 milliseconds. Lastly peak pressures obtained from analyses are compared to empirical equations in the literature and UFC 3-340-02 standard which provide unified facilities criteria for structures to resist the effects of accidental explosions. Also analyses' results such as displacements, stresses and strains obtained from both hydrostatic and blasting analysis models are compared to each other. It is highlighted from the study that blasting analysis model has more effective than the only hydrostatic analysis model. So it is highlighted from the study that the design of dams should be included the blast loads.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.971-976
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• 2001

Numerical studies were performed to investigate the seismic performance of Flat Plate System. For the numerical studies, a computer program for Finite Element analysis was developed. Parametric studies were performed to investigate variations of strength and ductility of flat plate with major parameters: gravity load, reinforcement ratio, thickness, column sizes. The numerical results provide a valuable insights on the behavior of flat plates. The comparison with the current design method shows that the current design methods for strength and ductility need to be improved in some aspects.